Beijing's commerce ministry on October 9 announced new controls on the export of rare-earth technologies, adding to regulations on a critical industry that has been a key source of tension between Beijing and Washington.

But just three weeks later, on the same day as talks between Chinese leader Xi Jinping and US President Donald Trump in South Korea, the ministry said it would freeze the measures for one year.

"China will suspend the implementation of the relevant export control measures... for one year, and will study and refine specific plans," an unnamed commerce ministry spokesperson said, adding the consensus was reached after trade talks this week in Malaysia.

China is the world's leading producer of the minerals used to make magnets crucial to the auto, electronics and defence industries. It has required licences for certain exports of the materials since April, hitting global manufacturing sectors.

Rare earths have been a major sticking point in recent trade negotiations between China and the United States, with Washington accusing Beijing of slow-walking export licence approvals.

The October 9 controls meant exporters would need to have obtained permission for technologies used for rare-earth mining and smelting, among other processing steps.

They also applied to technologies used in the "assembly, adjusting, maintenance, repair and upgrading of production lines", the commerce ministry said.